/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  package org.eclipse.aether.generator.gnupg.loaders;
  
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.io.IOException;
  import java.nio.file.Files;
  import java.nio.file.Path;
  import java.nio.file.Paths;
  
  import org.bouncycastle.util.encoders.Hex;
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.generator.gnupg.GnupgConfigurationKeys;
  import org.eclipse.aether.generator.gnupg.GnupgSignatureArtifactGeneratorFactory;
  import org.eclipse.aether.util.ConfigUtils;
  import org.eclipse.sisu.Priority;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static org.eclipse.aether.generator.gnupg.GnupgConfigurationKeys.CONFIG_PROP_KEY_FINGERPRINT;
  
  /**
   * Loader that looks for configuration.
   */
  @Singleton
  @Named(GpgConfLoader.NAME)
  @Priority(20)
  @SuppressWarnings("checkstyle:magicnumber")
  public final class GpgConfLoader implements GnupgSignatureArtifactGeneratorFactory.Loader {
      public static final String NAME = "conf";
  
      private final Logger logger = LoggerFactory.getLogger(getClass());
  
      /**
       * Maximum file size allowed to load (as we load it into heap).
       * <p>
       * This barrier exists to prevent us to load big/huge files, if this code is pointed at one
       * (by mistake or by malicious intent).
       *
       * @see <a href="https://wiki.gnupg.org/LargeKeys">Large Keys</a>
       */
      private static final long MAX_SIZE = 64 * 1000 + 1L;
  
      @Override
      public byte[] loadKeyRingMaterial(RepositorySystemSession session) throws IOException {
          Path keyPath = Paths.get(ConfigUtils.getString(
                  session,
                  GnupgConfigurationKeys.DEFAULT_KEY_FILE_PATH,
                  GnupgConfigurationKeys.CONFIG_PROP_KEY_FILE_PATH));
          if (!keyPath.isAbsolute()) {
              keyPath =
                      Paths.get(System.getProperty("user.home")).resolve(keyPath).toAbsolutePath();
          }
          if (Files.isRegularFile(keyPath)) {
              if (Files.size(keyPath) < MAX_SIZE) {
                  return Files.readAllBytes(keyPath);
              } else {
                  logger.warn("Refusing to load file {}; is larger than 64 kB", keyPath);
              }
          }
          return null;
      }
  
      @Override
      public byte[] loadKeyFingerprint(RepositorySystemSession session) {
          String keyFingerprint = ConfigUtils.getString(session, null, CONFIG_PROP_KEY_FINGERPRINT);
          if (keyFingerprint != null) {
              if (keyFingerprint.trim().length() == 40) {
                  return Hex.decode(keyFingerprint);
              } else {
                  throw new IllegalArgumentException(
                          "Key fingerprint configuration is wrong (hex encoded, 40 characters)");
              }
          }
          return null;
      }
  }